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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 271 records · Page 15
All sourcesNASA NTRSDOE OSTI
NASA NTRS1983

Drop motion in a rotating immiscible liquid body

The interaction of liquids is an important part of many processes and is often used for such purposes as causing a separation of solution components by mass transfer between phases, allowing a chemical reaction between liquids or their components, providing direct contact heating or cooling, or creating emulsions. Containerless space processing may well involve the interaction of liquids in the form of drops. For example it may be desirable to form an alloy in space by merger of two or more drops. Encapsulation of a volatile liquid by a second less volatile and immiscible liquid might be a means for avoiding volatilization. Rotation of such systems would enhance mixing where desirable and/or provide means for drop management. In this study, single drop behavior in rotating liquid bodies is studied experimentally.

Annamalai, P.↗
NASA NTRS1994

Space-based crystal growth and thermocapillary flow

The demand for larger crystals is increasing especially in applications associated with the electronic industry, where large and pure electronic crystals (notably silicon) are the essential material to make high-performance computer chips. Crystal growth under weightless conditions has been considered an ideal way to produce bigger and hopefully better crystals. One technique which may benefit from a microgravity environment is the float-zone crystal-growth process, a containerless method for producing high-quality electronic material. In this method, a rod of material to be refined is moved slowly through a heating device which melts a portion of it. Ideally, as the melt resolidifies it does so as a single crystal which is then used as substrate for building microelectronic devices. The possibility of contamination by contact with other material is reduced because of the 'float' configuration. However, since the weight of the material contained in the zone is supported by the surface-tension force, the size of the resulting crystal is limited in Earth-based productions; in fact, some materials have properties which prevent this process from being used to manufacture crystals of reasonable size. Consequently, there has been a great deal of interest in exploiting the microgravity environment of space to grow larger size crystals of electronic material using the float-zone method. In addition to allowing larger crystals to be grown, a microgravity environment would also significantly reduce the magnitude of convection induced by buoyancy forces during the melting state. This type of convection was once thought to be at least partially responsible for the presence of undesirable nonuniformities--called striations--in material properties observed in float-zone material. However, past experiments on crystal growth under weightless conditions found that even with the absence of gravity, the float-zone method sometimes still results striations. It is believed that another mechanism is playing a dominant role in the microgravity environment.

Shen, Yong-Hong↗
NASA NTRS1974

Electromagnetic containerless melting and solidification in the weightless environment

General facility concepts capable of processing the widest range of possible important containerless processing experiments within reasonable technology constraints are indicated. An important part of the work has been to make an up-to-date summary of these experiment possibilities. An attempt has been made to consider materials based on importance in terms of new scientific data or possible future commercial applications.

Frost, R. T.↗
DOE OSTI2022

Revisiting metastable immiscibility in SiO 2 –Al 2 O 3 : Structure and phase separation of supercooled liquids and glasses

Understanding and controlling liquid–liquid phase separation in aluminosilicates is crucial for optimizing glass properties. However, the metastable nature of aluminosilicates’ phase separation has made it difficult to study experimentally, and uncertainty persists regarding the compositional and temperature extents of the miscibility gap. Here, we present new experimental evidence that suggests a consolute temperature between 1440 and 1590°C and endmember compositions of 7 and 62 mol.% Al 2 O 3 for the phase-separated glasses. Using containerless melt processing, deeply supercooled liquids over the 0–60 mol.% Al 2 O 3 range are probed with in situ small- and wide-angle X-ray scattering, which simultaneously reveals changes in nanoscale density heterogeneity and atomic structure. Correlations between phase separation and atomic coordination environments are compared for liquids and glasses. Pair distribution function analysis shows mean O–(Si + Al) coordination increases with Al 2 O 3 content and decreases with temperature.

36 MATERIALS SCIENCE↗
NASA NTRS1976

Space processing in early Shuttle missions

The paper first reviews potential scientific and commercial benefits of space processing, and discusses roles of ground laboratory, sounding rocket, and Shuttle/Spacelab experimentation in carrying out space processing programs. Benefits which have been identified in such processes as containerless melting/solidification, electrophoresis, crystal growing, etc., and using such specific materials as tungsten, isoenzymes, single crystal silicon ribbon are utilized as specific examples in the above discussion. As a result, the paper identifies spectrum of specific objectives and implementation approaches for Shuttle/Spacelab experimentation. The paper then reviews currently planned Shuttle/Spacelab payload accommodations and traffic model. Finally, the paper matches experimentation approaches with Shuttle/Spacelab plans, and derives a possible schedule of missions in the 1979-1982 time frame using configurations with a high degree of automation where crew time for experiment involvement is limited.

Bloom, H. L.↗
NASA NTRS1982

Viscous Torques on a Levitating Body

New analytical expressions for viscous torque generated by orthogonal sound waves agree well with experiment. It is possible to calculate torque on an object levitated in a fluid. Levitation has applications in containerless materials processing, coating, and fabrication of small precision parts. Sound waves cause fluid particles to move in elliptical paths and induce azimuthal circulation in boundary layer, giving rise to time-averaged torque.

Busse, F.↗
NASA NTRS1987

Hybrid Electrostatic/Acoustic Levitator

Because electrostatic and acoustic forces independent of each other, hybrid levitator especially suitable for studies of drop dynamics. Like all-acoustic or all-electrostatic systems, also used in studies of containerless material processing. Vertical levitating force applied to sample by upper and lower electrodes. Torques or vibrational forces in horizontal plane applied by acoustic transducers. Electrically charged water drop about 4 mm in diameter levitated electrostatically and rotated acoustically until it assumed dumbell shape and broke apart.

Rhim, Won K.↗
NASA NTRS1987

Undercooling of bulk high temperature metals in the 100 meter drop tube

The 100-meter drop tube at NASA Marshall Space Flight Center provides an excellent opportunity to study the effects of containerless, microgravity processing in metals and alloys. In a series of experiments high melting temperature pure metals were melted in an electron beam furnace and dropped in vacuum. Sample sizes ranged from 0.175 to 1.2 grams. Large undercoolings on the order of 18 percent of the melting temperature were observed in Ti, Zr, Nb, Mo, Rh, Ta, and Pt. Undercoolings of 5 to 18 percent T(m) were observed in Ru and Ir. These undercooling results are consistent, repeatable, and occur in a high percentage of experiments. The experimental technique will be presented as well as the resultant microstructures of undercooled drops. The data will be discussed with respect to nucleation theory.

Hofmeister, William↗
NASA NTRS1987

Large charged drop levitation against gravity

A hybrid electrostatic-acoustic levitator that can levitate and manipulate a large liquid drop in one gravity is presented. To the authors' knowledge, this is the first time such large drops (up to 4 mm in diameter in the case of water) have been levitated against 1-gravity. This makes possible, for the first time, many new experiments both in space and in ground-based laboratories, such as 1)supercooling and superheating, 2) containerless crystal growth from various salt solutions or melts, 3) drop dynamics of oscillating or rotating liquid drops, 4) drop evaporation and Rayleigh bursting, and 5) containerless material processing in space. The digital control system, liquid drop launch process, principles of electrode design, and design of a multipurpose room temperature levitation chamber are described. Preliminary results that demonstrate drop oscillation and rotation, and crystal growth from supersaturated salt solutions are presented.

Rhim, Won-Kyu↗
NASA NTRS1989

Non-contact temperature measurement of a falling drop

The 105 meter drop tube at NASA-Marshall has been used in a number of experiments to determine the effects of containerless, microgravity processing on the undercooling and solidification behavior of metals and alloys. These experiments have been limited, however, because direct temperature measurement of the falling drops has not been available. Undercooling and nucleation temperatures are calculated from thermophysical properties based on droplet cooling models. In most cases these properties are not well known, particularly in the undercooled state. This results in a large amount of uncertainty in the determination of nucleation temperatures. If temperature measurement can be accomplished then the thermal history of the drops could be well documented. This would lead to a better understanding of the thermophysical and thermal radiative properties of undercooled melts. An effort to measure the temperature of a falling drop is under way. The technique uses two color pyrometry and high speed data acquisition. The approach is presented along with some preliminary data from drop tube experiments. The results from droplet cooling models is compared with noncontact temperature measurements.

Hofmeister, William↗
NASA NTRS1990

Real-time measurement of materials properties at high temperatures by laser produced plasmas

Determination of elemental composition and thermophysical properties of materials at high temperatures, as visualized in the context of containerless materials processing in a microgravity environment, presents a variety of unusual requirements owing to the thermal hazards and interferences from electromagnetic control fields. In addition, such information is intended for process control applications and thus the measurements must be real time in nature. A new technique is described which was developed for real time, in-situ determination of the elemental composition of molten metallic alloys such as specialty steel. The technique is based on time-resolved spectroscopy of a laser produced plasma (LPP) plume resulting from the interaction of a giant laser pulse with a material target. The sensitivity and precision were demonstrated to be comparable to, or better than, the conventional methods of analysis which are applicable only to post-mortem specimens sampled from a molten metal pool. The LPP technique can be applied widely to other materials composition analysis applications. The LPP technique is extremely information rich and therefore provides opportunities for extracting other physical properties in addition to the materials composition. The case in point is that it is possible to determine thermophysical properties of the target materials at high temperatures by monitoring generation and transport of acoustic pulses as well as a number of other fluid-dynamic processes triggered by the LPP event. By manipulation of the scaling properties of the laser-matter interaction, many different kinds of flow events, ranging from shock waves to surface waves to flow induced instabilities, can be generated in a controllable manner. Time-resolved detection of these events can lead to such thermophysical quantities as volume and shear viscosities, thermal conductivity, specific heat, mass density, and others.

Kim, Yong W.↗
NASA NTRS1990

The Marshall Space Flight Center Drop Tube Facility

The structural and instrumentation hardware and the improved experimental capabilities of a 105-m Drop Tube Facility are described. The structure is designed to provide a high-vacuum facility in a vertical orientation. The low-gravity environment obtained during free-fall and the containerless materials processing capabilities are discussed. Two furnaces, an electron-beam and an electromagnetic levitator, are used to melt metallic samples in a process environment ranging from 10 to the -6th torr to 1 atm. Specifics of the vacuum control and gas delivery systems are provided. The experimental instrumentation and data acquisition systems used to perform predrop and in-flight measurements of the melting and solidification process are discussed. Typical experimental results are presented as an indicator of the performance of the Drop Tube Facility.

Rathz, Thomas J.↗
NASA NTRS2016

Levitation Technology in International Space Station Research

The International Space Station (ISS) is a unique multidisciplinary orbiting laboratory for science and technology research, enabling discoveries that benefit life on Earth and exploration of the universe. ISS facilities for containerless sample processing in Materials Science experiments include levitation devices with specimen positioning control while reducing containment vessel contamination. For example, ESA's EML (ElectroMagnetic Levitator), is used for melting and solidification of conductive metals, alloys, or semiconductors in ultra-high vacuum, or in high-purity gaseous atmospheres. Sample heating and positioning are accomplished through electromagnetic fields generated by a coil system. EML applications cover investigation of solidification and microstructural formation, evaluation of thermophysical properties of highly reactive metals (whose properties can be very sensitive to contamination), and examination of undercooled liquid metals to understand metastable phase convection and influence convection on structural changes. MSL utilization includes development of novel light-weight, high-performance materials. Another facility, JAXA's ELF (Electrostatic Levitation Furnace), is used to perform high temperature melting while avoiding chemical reactions with crucibles by levitating a sample through Coulomb force. ELF is capable of measuring density, surface tension, and viscosity of samples at high temperatures. One of the initial ELF investigations, Interfacial Energy-1, is aimed at clarification of interfacial phenomena between molten steels and oxide melts with industrial applications in control processes for liquid mixing. In addition to these Materials Science facilities, other ISS investigations that involve levitation employ it for biological research. For example, NASA's "Magnetic 3D Culturing and Bioprinting" investigation uses magnetic levitation for three-dimensional culturing and positioning of magnetized cells to generate spheroid assemblies for biomedical applications. Levitation is also used as a modeled microgravity ground analog in the NASA OsteoOmics ISS investigation, which tests whether magnetic levitation accurately simulates microgravity conditions by studying gravitational regulation of osteoblast and osteoclast genomics and metabolism. Elucidating the cellular mechanisms of bone loss in microgravity contributes to the understanding of bone loss in medical disorders on Earth, which may lead to development of preventive or therapeutic countermeasures. Thus, the ISS state-of-the-art laboratory offers various levitation capability platforms with applications for innovative research in Materials and Life Sciences disciplines, with benefits for humanity.

Guinart-Ramirez, Y.↗
DOE OSTI2012

Acoustic levitation

Scientists at Argonne National Laboratory have discovered a way to use sound waves to levitate individual droplets of solutions containing different pharmaceuticals. While the connection between levitation and drug development may not be immediately apparent, a special relationship emerges at the molecular level. Read more: http://www.anl.gov/articles/no-magic-show-real-world-levitation-inspire-better-pharmaceuticals

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
NASA NTRS1986

Making Highly Pure Glass Rods

Proposed quasi-containerless method for making glass rods or fibers minimizes contact between processing equipment and product. Method allows greater range of product sizes and shapes than achieved in experiments on containerless processing. Molten zone established in polycrystalline rod. Furnace sections separated, and glass rod solidifies between them. Clamp supports solid glass as it grows in length. Pulling clamp rapidly away from melt draws glass fiber. Fiber diameter controlled by adjustment of pulling rate.

Naumann, R. J.↗